Add a method `AbtractCvodeCell::SetMaxTimestep(double)`. This just calls `SetTimestep()` (which does set a max timestep not the timestep). Method added to avoid unclear test/user code. Maybe 
`AbtractCvodeCell::SetTimestep(double)` should be removed sometime.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20970 b5f69653-2bf5-0310-8201-b0dafb8e1405
Prasvandal

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@20973 b5f69653-2bf5-0310-8201-b0dafb8e1405